You can't compare the two. Completely different animals.
The difference between MA3 AM digital and DTV is available bandwidth, DTV uses 6 MHz per channel with enough headroom for redundant packets/Bit Error Correction. Plus noise floor at UHF frequencies is much-much less than Medium Wave.
Another thing to consider, is DTV reception has a standard assumption formula for average receive antenna gain and elevation:
https://transition.fcc.gov/oet/info/documents/reports/SHVERA/SHVERA-FCC-05-199.pdf
MA3 has no such assumptions, because of a mobile/portable reception environment, and unlimited variations in antenna types and receiver gain with varying levels of environmental noise.